Egg carton that is tamper evident

ABSTRACT

The present invention provides an egg carton having a tamper evident locking mechanism, and a process for making a tamper evident carton. The carton provides, in various embodiments, a simplified construction with a tamper evident locking mechanism that both resists inadvertent opening, and once opened, alters the appearance or integrity of the carton itself.

FIELD OF THE INVENTION

The present invention relates to a plastic egg carton having a tamper evident locking mechanism.

BACKGROUND OF THE INVENTION

Egg cartons typically include a lid and a base, hingedly connected along one edge, allowing the container to be opened and closed repeatedly to access the contents. The hinge allows eggs to be selectively retrieved from the carton without risk of dropping or misplacing the lid. The hinge also assists in guiding the lid into a closed and secured position.

Egg cartons are often composed of plastic materials as plastics are non-absorbent and allow for inexpensive and rapid mass production while also allowing structural reinforcing elements to be included in the carton's construction. For example, the hinge may be provided as part of a peripheral flange on the carton perimeter for ease of manufacturing as well as the added rigidity a flanged hinge brings to the egg carton. The increased rigidity reduces the risk of the carton collapsing when in a vertically stacked configuration, or from collapsing due to lateral forces being applied to the container (e.g., when a consumer grabs a closed container in one hand and squeezes inwardly).

Grabbing the carton in one hand poses other problems, such as the risk of the lid popping off the base. This sudden and inadvertent opening of the carton may cause eggs to drop out of the carton, or cause the consumer to lose their grip on the carton and drop it. Either event effectively ends the life of the carton and its contents (rendering the carton unfit for sale), while also creating a major mess (broken eggs) for the retailer to cleanup.

For this reason egg cartons typically include one or more tabs, locking nubs, recesses or openings (slots) on the base and lid respectively for securing the lid to the base. However, these multiple aligning and locking mechanisms complicate the manufacturing process and will not always prevent inadvertent opening. Nor do they render the carton tamper evident as these mechanisms can be engaged and disengaged repeatedly with no evidence of such prior disengagement.

Thus, there is a need for a hinged plastic egg carton that resists opening when a customer is handling it during purchase, and during the prior shipping and handling stages, while still providing the required structural and aesthetic design features. There is also a need to provide a tamper evident egg carton with these advantages. Preferably the carton does not require the use of specially configured packing, shipping or handling equipment.

SUMMARY OF THE INVENTION

The present invention provides an egg carton having a tamper evident locking mechanism, and a process for making a tamper evident carton. The carton provides, in various embodiments, a simplified construction with a tamper evident locking mechanism that both resists inadvertent opening, and once opened, alters the appearance or integrity of the carton itself. The carton can be processed on standard packing and handling equipment. The carton can be configured to receive different size eggs (e.g., medium, large, extra-large and jumbo), and fit within standard shipping containers, e.g., full (30 dozen, 12 egg cartons), one-half (15 dozen, 12 egg cartons), or other wire cases. The cartons can be filled either manually or on standard automatic equipment that places eggs in the egg-receiving cells of the base and then closes the closure flap and lid over the base while the tamper evident sealing mechanism automatically seals the lid to the base. The tamper evident sealing mechanism is attached to the lid in a manner that does not interfere with the stacking of empty cartons, and automatically seals the carton when the carton is closed.

In one embodiment, a plastic tamper-evident egg carton is provided, the carton comprising:

a base, a lid and a closure flap;

the closure flap having opposing interior and exterior surfaces and a closure nub projecting from the exterior flap surface;

the base having an interior surface defined by a plurality of egg-receiving cells and an upper base perimeter surrounding the plurality of cells, the upper base perimeter having opposing front and rear base edges;

the lid having an interior surface defined by a top wall, sidewalls extending downwardly from the top wall and a lower lid perimeter, the lower lid perimeter having opposing front and rear lid edges, the rear lid edge and rear base edge being joined by a hinge allowing the lid to be moved from an open carton position exposing the interior of the base, to a closed carton position over the base interior, one of the lid sidewalls being disposed adjacent the front lid edge and having a slot configured for receiving the closure nub on the flap when the lid and base are in the closed carton position;

the closure flap having a perimeter with opposing top and bottom flap edges, the bottom flap edge and the front base edge being joined by a hinge allowing the flap to be moved from a first open flap position exposing the interior of the base to a second closed flap position under an interior surface of the one lid sidewall when the base and lid are in the closed carton position;

a sealing member attached to an exterior surface of the one lid sidewall and covering the slot, wherein in the closed carton position, the sealing member is configured to seal to the nub projecting through the slot thus rendering the carton tamper evident.

In such an embodiment the slot has a slot perimeter and the sealing member has an adhesive interior surface that is attached to an area on the exterior surface of the one lid sidewall surrounding at least a portion of the slot perimeter.

In such an embodiment the area surrounds the entire slot perimeter.

In such an embodiment the adhesive is a single use adhesive such that detaching the sealing member from the exterior surface of the one lid sidewall renders the adhesive no longer able to adhesively reattach to the exterior surface.

In such an embodiment the closed carton has a rectilinear perimeter having a length, width and height, and the carton has one nub and one slot centrally located in the length direction.

In such an embodiment the egg carton is a bi-fold egg carton.

In such an embodiment the cells comprise an array of 2×6, 2×5, 2×4, 2×3 or 2×2 cells.

In such an embodiment the nub comprises a front nub face and nub sidewall, and the nub sidewall spacing the front nub face from the outer face of the closure flap. In such an embodiment the slot has a slot perimeter with opposing side edges, and the sealing member has an adhesive outer surface configured to adhere to an area of the sealing surface adjacent the two opposing side edges.

In such an embodiment the sealing strip has one or more areas of perforations, providing a weakened area that tears to provide tamper evidence.

In one embodiment, a method of rendering an egg carton tamper proof is provided, the method comprising:

providing the egg carton and sealing member of claim 1,

adhering the sealing member to the exterior surface of the one lid sidewall and covering the slot,

rotating the lid about the rear hinge to the closed carton position over the base interior, wherein the closure nub on the flap pushes through the slot on the lid when the lid and base are moved to the closed carton position and seals the sealing member to nub thus rendering the carton tamper evident.

These and other features of the invention will be better understood from the following detailed descriptions and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view an egg carton according to one embodiment of the invention, showing a partially filled (two representative eggs E are shown) egg carton prior to being closed and sealed, the carton having a lid, base and closure flap, and including a tamper evident locking mechanism on the lid and closure flap;

FIG. 2 is a front perspective view of the egg carton of FIG. 1 after being filled and closed, showing the tamper evident locking mechanism now sealing the carton in the closed position, rendering it tamper evident and resistant to inadvertent opening;

FIG. 3 is an enlarged top perspective view of a portion of the closed carton of FIG. 2, showing the tamper evident locking mechanism;

FIG. 4 is a front elevational view of the closed carton of FIG. 2, showing the tamper evident locking mechanism;

FIG. 5 is a top plan view of the closed carton of FIG. 2;

FIG. 6A is a cross-sectional view of the open and unfilled carton of FIG. 1, while FIG. 6B is a cross-sectional view of the filled and closed carton of FIG. 5 taken along section line 6B-6B showing the tamper evident locking mechanism;

FIG. 7 is a cross-sectional view of two open and empty stacked cartons of FIG. 1, showing that the tamper evident locking mechanism does not interfere with the stacking of empty cartons;

FIG. 8 is an enlarged top perspective view, similar to FIG. 3, of another embodiment of a sealing strip having perforations that when torn, provide evidence of tampering.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1-7 illustrate a bi-fold plastic egg carton 10 according to one embodiment of the invention, the carton being configured to hold 12 eggs in a 2×6 rectilinear array of cells, with each egg in an individual cell. FIG. 1 shows the carton partially open, with two representative eggs E shown in two of the cell pockets 20. FIG. 6B is a cross section of the closed and sealed carton showing, in dashed lines, two eggs E in two of the cells. Egg cartons of this type, but without the tamper evident locking mechanism of the present invention, are described in Ramirez US 2013/0048527 the disclosure of which is herein incorporated by reference in its entirety.

As shown in FIGS. 1-2, the carton 10 includes a tamper evident locking mechanism that includes a locking nub 56, a locking slot (opening) 40, and a sealing member 60 disposed over the locking slot as described in greater detail below. FIG. 1 shows the carton prior to closure, with a closure flap 16 disposed over (above) the interior 18 of the base 12 prior to closing the lid 14. In actual use, each of the carton base cells 20 would be filled with an egg E prior to closure. FIG. 2 shows the carton in the closed position, after the lid 14 is closed down and locked over the assembled closure flap 16 and base 12, with the sealing member 60 now sealed to a front face 57 of the locking nub 56 thus rendering the closed carton tamper proof. FIGS. 3-6 show various views of the sealing member sealed to the closed carton, as described in greater detail below.

The locking nub 56 projects outwardly from a front exterior surface 52 of the closure flap 16, and is sized to fit into a slot 40 in a front sidewall 34F of the lid 14 when the lid is closed over the base 12 and flap 16. In the closed position (see FIGS. 2 and 6B), the front planar surface 52 of the flap lies beneath and in mating planar contact with an interior planar surface 30 of the lid front wall 34F. As the nub front wall 57 is pushed through the slot 40 (during rotation of the lid to the closed position) the nub front wall 57 automatically engages a rear planar surface 62 of the sealing strip 60 that is adhesive, thus automatically sealing the nub front face 57 to the adhesive strip surface 62 (see FIG. 3). This both locks the lid to the base and provides a tamper evident seal. To open the carton, the user peels back the adhesive strip 60 from the lid front wall 34F and from the front face 57 of the nub, thus releasing the strip from the nub and allowing the nub to be retracted from the slot 40, to unlock the carton. The carton can now be opened by rotating the lid 14 outwardly about a rear hinge 27. The strip 60 does not readily re-adhere to the carton, thus providing evidence that the carton has already been opened (i.e., tampered with). In one embodiment, the adhesive may detach part of the front wall 34F of the lid to prevent such re-adherence, preferably without preventing further engagement and disengagement of the locking nub 56 in the slot 40 (so the user can continue to lock and unlock the carton, but without the sealing strip).

The materials and dimensions of the strip 60 can vary based on the overall carton design and other factors. Preferably a single nub and a single slot are provided centrally along the length L direction of the carton (see FIG. 5) on the front faces 52 and 34F of the flap and lid respectively, and the strip is sized to cover both the slot 40 and an area A on the lid front wall 34F surrounding at least some portion of the slot perimeter 41. In the present embodiment the strip covers an area A of the front lid face 34F surrounding at least two opposing sides of the slot, shown in FIG. 1 as areas AL and AR to the left and right of the slot perimeter 41. During closure, when the nub front face 57 pushes through the slot 40 it engages a central portion 64C of the strip (as best shown in FIG. 3), while some portion of the front face lid areas AL and AR may be pulled away (separated) from the strip 64 thus forming, for example, a bridged configuration of the strip on either side of the nub front face 57. The central strip portion 64C remains adhered to nub face 57, and opposing left and right end areas 65L and 65R of the strip remain adhered to the lid front face 34F on opposing sides of the slot 40. The strip itself may stretch to accommodate the depth of the nub (the distance by which the nub front face 57 projects outwardly from the lid front face 34F, as defined by the nub sidewall 58) as the nub pushes through the slot, thus putting the strip 60 in tension across the slot 40. The materials, dimensions and shape of the nub, slot and strip can be varied depending on the size and weight of the carton and the eggs to ensure that the carton will not inadvertently open when subject to typical forces encountered during shipment, stacking and handling of the carton by the retailer and the end user. These and other variations will be apparent from the disclosure herein.

Returning more generally to the overall carton design, the carton is formed as an integral body that includes a base 12, a lid 14, and a closure flap 16. The base has an upwardly facing (interior) surface 19 that defines an interior volume 18 of the base, and comprises a plurality of egg-receiving cells 20 arranged in a 2×6 matrix. The base has a perimeter of rectilinear shape, including opposing front and rear longitudinal edges 24F and 24R, and opposing left and right side edges 23L and 23R. The lid 14 also has a rectilinear perimeter and is connected to the rear longitudinal edge 24R of the base 12 via a rear hinge 27 The carton further includes a flap 16 connected via a front hinge 26 to the opposing front longitudinal edge 24F of the base. The front and rear hinges 26, 27 each have a respective axial hinge line that lies in or parallel to a hinge reference plane HRP when the carton is in the fully open position (see FIG. 6A), the HRP being disposed parallel to a base reference plane BRP in which a lowermost standing surface 21 of the base rests. In use, the flap 16 is rotated about front hinge 26 (in the direction of arrow A1 in FIG. 6A) from an open position (shown in FIG. 6A, the open position allowing full access to the interior of the base such that eggs can be inserted into the base cells 20 of the open carton) moving toward the interior 18 of the base to a second position (shown in FIG. 6B) that will allow the flap 16 to fit underneath the lid 14 of the closed carton, followed by rotating the lid 20 about the rear hinge 27 (in the direction of arrow A2 in FIG. 6A) downwardly over the interior 18 of the base to a closed position on top of the assembled flap and base (shown in FIG. 6B). In the closed configuration, the rectangular carton 10 occupies a volume having a length L, a width W, and a height H defined by its outermost perimeter P (see FIGS. 4-5 where H is transverse to the base reference plane BRP on which the base of the assembled carton rests).

As shown in FIG. 5, the lid 14 is also generally rectilinear in shape as defined by transverse W and L directions, and includes two opposing (left and right) lateral end walls 24L and 24R, extending between and connecting two opposing longitudinal front and rear walls 23F and 23R. In each of the four corners 25 of the lid, where a front or rear wall 23 joins an end wall 24, there is formed a radiused corner. A peripheral flange 39 is formed around the entire lower end of the lid, extending substantially transversely (parallel to the BRP) from the bottom edge of each of the opposing front and walls 23F and 23R and end walls 24L and 24R. This substantially flat (planar) lid flange 39 has a lower-facing surface that mates with an upper-facing planar surface of the peripheral base flange 29. The mating (face to face engagement) of the peripheral flanges 39, 29 of the lid and base increase the mechanical strength (stiffness) of the carton, enabling multiple cartons to be stacked vertically one on top another, and providing lateral reinforcement to prevent collapse of the carton when for example, grabbed in one hand by the consumer or when lateral forces are otherwise applied to the carton. The peripheral flanges 29, 39 define the outermost rectilinear perimeter P of the carton, and assist in de-nesting of individual cartons from a stack of empty cartons.

In the present embodiment, the rear hinge connection 27 connecting the lid to the base includes an axial folded hinge line aligned along the length L direction of the carton. The hinge connection 27 also includes abutting planar wall portions of the base and lid flanges 29, 39 adjacent either side of the axial hinge line, respectively, having planar wall surfaces lying in a common hinge reference plane HRP when the lid and base are in the open position (FIG. 6A). The upper planar wall surfaces 29 and 39 are in mating (face-to-face) planar engagement, while the folded hinge line of the front hinge 26 forms a front edge of the carton perimeter P, when the lid and base are in the closed position (see FIGS. 2 and 6B).

FIG. 7 illustrates another advantage of the tamper evident locking mechanism, namely that a plurality of empty and open cartons, having the sealing member already applied over the slot, can be stacked without the sealing mechanism, the nub and the slot interfering with such stacking. FIG. 7 shows two such stacked cartons, an upper carton 10U stacked over the interior of the lower carton 10L.

In one embodiment, the sealing strip is perforated, providing a weakened area most likely to tear, such that when a person attempts to open the carton by pulling on the strip, the perforations tear and provide evident of tampering. FIG. 8 shows one such embodiment, in a view similar to FIG. 3, wherein two perforated lines PF extend across the width of the sealing strip 64 (in the height direction of the carton), disposed on either side of the central strip area 64C that engages the nub face 57. A user pulling on the strip may insert a finger underneath the strip and tear one or both perforated lines PF in the course of pulling on the strip to open the carton. Alternatively a person may pull on one end of the strip, trying to peel it off the carton lid, and again the perforated lines would be a weakened area most likely to tear. The perforation(s) may be provided in other locations in other embodiments.

Variations of the foregoing embodiments will be apparent to the skilled person.

In the present embodiment, the carton 10 is integrally formed from a sheet of molded plastic material, e.g., a clear solid sheet of polyester, such as polyethylene terephthalate (PET); alternative polymers are described below. The sheet from which the carton is integrally molded can be shaped (formed) by a molding process, e.g., thermal pressure forming with a plug assist in a mold to form the shaped lid, base, and flap portions, the lid and base each including a peripheral flange, and then removing (trimming) any remaining portions of the sheet to form an integral carton. More specifically, the carton may be formed between a female die cavity and a cutting edge punch having a knife edge, the cavity and punch being brought together to sever (cut) the carton from the sheet. Other methods are known and can be used for forming the carton.

In various embodiments, the egg carton may have a different sized array of egg-receiving cells, such as a 2×6, 2×5, 2×4, 2×3 or 2×2 array.

In various embodiments, the plastic material of the egg carton is selected from foam and non-foam materials. The plastic material of the egg carton may be one or more of polystyrene (e.g., polystyrene foam), polyester (e.g., polyethylene terephthalate (PET)), polyolefin (e.g., polyethylene (PE)), polypropylene (PP), or poly(lactic acid) (PLA), including homopolymers, copolymers, and blends thereof, and including virgin and reclaimed (recycled) materials.

In various embodiments, the strip 60 may be formed of paper, polystyrene (PS) polyvinylchloride (PVC), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET) or combinations thereof and the adhesive may comprise polyacrylic dispersions, polystyrene-butadiene copolymer dispersions, polyethylene-vinyl acetate copolymer dispersions, and natural or synthetic rubbers.

While specific embodiments of the present invention have been shown and described it will be apparent that many modifications can be made thereto without departing from the scope of the invention. Accordingly, the invention is not limited by the foregoing description. 

What is claimed is:
 1. A plastic tamper-evident egg carton comprising: a base, a lid and a closure flap; the closure flap having opposing interior and exterior surfaces and a closure nub projecting from the exterior flap surface; the base having an interior surface defined by a plurality of egg-receiving cells and an upper base perimeter surrounding the plurality of cells, the upper base perimeter having opposing front and rear base edges; the lid having an interior surface defined by a top wall, sidewalls extending downwardly from the top wall and a lower lid perimeter, the lower lid perimeter having opposing front and rear lid edges, the rear lid edge and rear base edge being joined by a hinge allowing the lid to be moved from an open carton position exposing the interior of the base, to a closed carton position over the base interior, one of the lid sidewalls being disposed adjacent the front lid edge and having a slot configured for receiving the closure nub on the flap when the lid and base are in the closed carton position; the closure flap having a perimeter with opposing top and bottom flap edges, the bottom flap edge and the front base edge being joined by a hinge allowing the flap to be moved from a first open flap position exposing the interior of the base to a second closed flap position under an interior surface of the one lid sidewall when the base and lid are in the closed carton position; a sealing member attached to an exterior surface of the one lid sidewall and covering the slot, wherein in the closed carton position, the sealing member is configured to seal to the nub projecting through the slot thus rendering the carton tamper evident.
 2. The egg carton of claim 1 wherein the slot has a slot perimeter and the sealing member has an adhesive interior surface that is attached to an area on the exterior surface of the one lid sidewall surrounding at least a portion of the slot perimeter.
 3. The egg carton of claim 2 wherein the area surrounds the entire slot perimeter.
 4. The egg carton of claim 2 wherein the adhesive is a single use adhesive such that detaching the sealing member from the exterior surface of the one lid sidewall renders the adhesive no longer able to adhesively reattach to the exterior surface.
 5. The egg carton of claim 1 wherein the closed carton has a rectilinear perimeter having a length, width and height, and the carton has one nub and one slot centrally located in the length direction.
 6. The egg carton of claim 1 wherein the egg carton is a bi-fold egg carton.
 7. The egg carton of claim 6 wherein the cells comprise an array of 2×6, 2×5, 2×4, 2×3 or 2×2 cells.
 8. The egg carton of claim 1 wherein the nub comprises a front nub face and nub sidewall, and the nub sidewall spacing the front nub face from the outer face of the closure flap.
 9. The egg carton of claim 1 wherein the slot has a slot perimeter with opposing side edges, and the sealing member has an adhesive outer surface configured to adhere to an area of the sealing surface adjacent the two opposing side edges.
 10. The egg carton of claim 1, wherein the sealing strip has one or more areas of perforations, providing a weakened area that tears to provide tamper evidence.
 11. A method of rendering an egg carton tamper proof comprising: providing the egg carton and sealing member of claim 1, adhering the sealing member to the exterior surface of the one lid sidewall and covering the slot, rotating the lid about the rear hinge to the closed carton position over the base interior, wherein the closure nub on the flap pushes through the slot on the lid when the lid and base are moved to the closed carton position and seals the sealing member to nub thus rendering the carton tamper evident. 